Nope - that’s just stupid.
But what I am doing, is changing the way I drive. I drive slower (never going over 55), accelerating slowly (not gunning it), slowing down to stop sooner (coasting more)...things that help lower gas mileage that I wasn’t doing before.
Y'know, it's funny. On my mail route, my Explorer gets about 12-ish mpg. I go around 87 miles. If I HUSTLE, like chewing-gum-panting-rushing between mailboxes, I can shave off a half hour from my route. You'd think I'd trash my MPG. Nope. I get home with MORE gas if I drive like that. If I take my time, I use almost 1/8th tank MORE fuel to go the same distance.
WAY more damaging to the vehicle to drive like that, though. Brakes, suspension, etc. take a knockin'. Gas is cheaper.
The longer you go between refills, the more you shell out on the spot. First because the price is a function of time (the longer you wait the higher the price goes) and secondly, the emptier tank just takes more to fill it up.
There is a technique of driving that is called “hypermileage” - shifting into neutral and coasting to a stop, feathering only lightly on the brakes, while trying to still be moving when the light changes, getting the vehicle into the highest gear at the lowest speed practical (watch the tachometer and speedometer to determine the shift points on the automatic transmission), and use little tricks like filling up when the air is cool, commencing your trip before the day warms up so very much.
Out on the highway, the cruise control is WAY smarter than you are, especially coupled with the computer engine controls. Again watching the tachometer, try to keep the engine speed below a point around 2,000 rpm, more important actually than the speed.
And if you have an “instantaneous” mileage readout, try to keep it up in the higher ranges. Neat little psychological trick right there.
Vacuum gauges used to be a fairly good guide, but nobody uses them any more.